(a) Field of the Invention
The present invention relates to an improved adjustable keyboard shelf, more particularly to an adjustable keyboard shelf that is provided with an ergonomically designed palm rest assembly to allow for height and/or elevation adjustment and that can hold a computer keyboard firmly in position and prevent keyboard from moving during operation.
(b) Description of the Prior Art
Computer keyboards are basic peripherals of computers for input purposes. Although there are other input devices like mouse, track balls, and digital boards, undeniably, keyboards are the most important input tool. Therefore, conventional computer tables are mostly equipped with a retractable adjustable keyboard shelf on which a keyboard can be placed. For those who have to use keyboards for a long period of time every day, they may have sore wrists. Prolonged use may also cause injury to the wrists. Therefore, a kind of multi-media keyboard has been developed in recent years to include a palm rest. However, as keyboards with palm rests are usually bulky, not closable, and relatively costly, standard keyboards are more popular among users. Besides, existing keyboard shelves are now generally provided with a palm rest for use with standard keyboards.
U.S. Pat. No. 5,547,154 discloses a wrist rest assembly that projects from a front end of a rectangular tray. The wrist rest assembly is disposed on a base assembly and connected to a detachable elongate pad. The pad includes a layer of gel coated with a covering layer. A keyboard is placed on the tray to abut against a vertical wall at a rear end of the wrist rest means. In use, the pad is rotatable about 180 degrees and then connected to the base assembly to allow operation at two different heights so as to adapt to the requirements of different users.
However, the wrist rest assembly in said U.S. patent can only allow two-stage height adjustment and does not allow for adjustment of its angle of elevation. It cannot, therefore, be adapted for different types of keyboards. In addition, conventional adjustable keyboard shelves do not have other functions than placement of the keyboard. Therefore, a keyboard placed on a keyboard shelf may easily move.